I have to go for GWAPT certification but as found on SANS website, the course modules cost is pretty high. Will request you all if anyone can help me providing the course modules.Any help in this regard is duly appreciated.

Have a play with the Samurai Web Testing Framework as Kevin Johnson, the course author, was one of the people that designed it. Plus if you read the course description, you find some of the other tools used in the course and can find plenty of reading for them on the web.

If you have to do the training or take the exam, have you looked at the vLive option from SANS? They have recently had a number of discount codes for some of the other vLive courses.

Depending on your experience levels with web applications and attacking, the challenge path dynamik is suggesting is one way to go. However, I'd suggest you'd need to have been working in the web app pentest space for a couple of years before attempting that.